An herbicide often used with complimentary genetically modified plants (trademark: Liberty)

Toxic to all but a few plants, glufosinate (an ammonium salt of the amino acid phosphinotricin) is used as an active ingredient in herbicides. It works by blocking the enzyme glutamine synthase, a central enzyme in plant metabolism. This causes a build-up of ammonia, which is toxic to the plant. The affected plant dies within a few days.

Glufosinate is readily biodegradeable with a half-life in soil of 3-20 days, depending on environmental conditions. No accumulation of the herbicide or its short-lived breakdown products has yet been observed.

Glufosinate has been used since 1984 as a non-selective (broad-spectrum) herbicide primarily in nursuries, vineyards, and orchards. For a long time, the use of non-selective herbicides for field crops was very limited, because the herbicides would kill the crops themselves.

The LibertyLink herbicide resistance system has opened up new possibilities for glufosinate. Several important crops have been given tolerance to glufosinate with genetic engineering. These transgenic plants contain a bacterial gene encoding an enzyme that makes the herbicide harmless.